The filling of bulk bags, also known as flexible intermediate bulk containers or “FIBCs” is typically accomplished by a filling machine having means for hanging the bag and connecting the bag to the nozzle of a discharge apparatus. In addition, the filling machine may be provided with means for weighing the bag as it is being filled, means for raising and lowering the bag, means for vibrating and compacting the contents of the bag during filling, and means for controlling discharge of particulate material into the atmosphere during filling of the bag. Bag filling machines incorporating one or more of these features are disclosed in U.S. Pat. No. 6,564,534 (Poulton et al.), U.S Pat. No. 5,336,853 (Davidson) and U.S. Pat. No. 4,718,464 (Delves et al.).
One disadvantage of existing bag filling machines is that they are not easily adapted to suit the varying needs of users. For example, some users may not require means for vibrating the bag or weighing the bag and its contents, whereas other users may require a filling machine having all of the above features. In general, the inventors have found that it is difficult or impossible to retrofit additional components onto most existing bag filling machines. Likewise, it may be difficult to eliminate components which are not required by a specific user. This not only limits the range of choices available to the user, but can increase cost due to the fact that it may be necessary to design a separate filling machine for each application. Furthermore, a user wishing to upgrade to a filling machine having enhanced features will be forced to purchase a new machine where retrofitting the additional components is not possible.
The inventors have also found that many filling machines employ weighing mechanisms which are unnecessarily complex. This can result in poor reliability and high cost. There remains a need for simpler, more robust filling machines which are preferably of modular construction in order to meet the varying needs of filling machine users.